Compass-protractor.



Patented Nov. I3, i900. J. D. BARBIE.

COMPASS PRTRACTDR.

(Application led Apr.

(No Model.)

.IOIIN D. BARBIE, OF LOS ANGELES, CALIFORNIA.

COMPASSMPROTRACTOH.

SPECIFICATION forming' part of Letters Patent No. 661,483, datedNovember 13, 1900.

Application led April 12,1900. berial No. 12,567. (No model.)

T0 fir/ZZ when@ it' may concern:

Be it known that I, JOHN D. BARBIE, a citizen of the United States,residing` at Los Angeles, in the county of Los Angeles and State ofCalifornia, have invented certain new and useful Improvements inOompass-Protractors; and I do declare the following to be a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the saine.

My invention relates to compass-protractors `for use in the school-roon1on the blackboard in drawing circles or any fraction of a circle, and itis designed to take the place of a compass and protractor as at presentused in school-rooms and also of the more frequently used piece ofcrayon tied on a string and used by holding one end of said stringagainst the blackboard While with the crayon attached to the other endof the string the pupil makes the circle as best he can, and when it isdesired to take a certain number of degrees of a circle on saidblackboard one pupilholds the protractor on the blackboard, Whileanother pupil is required to hold one end of the string on the center ofthe protractor With one hand and With the other hand he takes as manydegrees of the circle as may be desired.

The object of my improvements is to produce a compass-protractor whichis simple in construction and easy of application in drawing circles orfractions of circles on a blackboard with the ordinary chalk crayons nowin use.

Vith this object in view the invention consists in the construction andnovel combination of the parts of the same, as hereinafter fullydescribed and claimed.

In the drawings hereto annexed and forining part of this speciiication,Figure 1 is a view in perspective of the improved compassprotractor.Fig. 2 is a detail View of the protractor proper. Fig. 3 is a sectionaldetail view of the slotted spring-pressed crayonholding tube seated inthe sleeve on the stationary handle. Fig. e is a detail view of therevolving sleeve Which iits over and is slipped upon the stationarysleeve in the stationary 5o crayon-holder and is provided With an inbythe string with the center-1na1king handle of the compass-protractor.Fig. 6 is a sectional view of the protractor, taken on the line .cc inFig. 2. Fig. 7 is a vertical sectional view through the parts shown inFig. l. Fig. 8 is a vertical sectional View through the chalk or crayonholder.

Referring by numerals to the accompanying drawings, 1 designates thecentral crayonholding tube, which is provided with longitudinaldiametrically-opposed slots 1,eXtend ing nearly throughout its length,and which is held in its normally-projected position in a sleeve 2,forming part of the center-marking handle 2, by a transverse pin 2h,secured in said sleeve 2. A spiral spring 2c within the sleeve 2, at theupper end of the latter, normally projects the crayon-holder 1 outwardlyagainst said transverse pin 2b; but when the crayon in the point of saidcrayon-holding tube 1 is pressed against the face of the blackboard thespring yields to pressure and the crayon holding tube recedes Within thesleeve 2.

The sleeve 2 is provided with bearings 20, upon Which the revolvingsleeve 3 bears. These bearings lessen the friction and allow the sleeve3 to revolve as lightly as possible. Immediately surrounding the sleeve3 is the revolving drum 4, Which latter is provided at its upper endwith a milled flange e by which to turn it to wind the measuring-cord tbthere on Whenever said cord 4t may have been either partially or whollyunwound from said drum. At its lower end the revolving sleeve 3 isprovid ed with an annular flange 10. With the annular flange 10 isformed an integral radially-projecting arm 11, which is provided Withlugs or ears at opposite points about midway of its length to receivethe journals of an eccentric cord-clamp 12.

The protractor proper is slightly convex, as shown in Fig. 6, in orderto lessen its tendency to slip, and is provided with an axial openingand radial view-openings. In prac- IOO tice it is scaled to the threehundred and sixty degrees of a circle.

The measuring-cord 4b is colored in lengths of inches or half-inches inorder that it may be practically used for measuring.

The crayon-holder forming the pencil p0rtion of the compass-protractorcomprises a handle bored axially fora portion of its length, said boredportion being sawed along intersecting diametrical lines to formcrayon-holding fingers 13, (four in number,) which are surrounded by asliding sleeve 14, which loosely fits the contour of said finger portionand when moved forward on said fingers com,- press them upon the crayonto hold it in position for use. The sliding sleeve 14 is provided withconcentric rings or anges 15 16, between which a loose ring 17, havingan attaching-arm 18 for connecting the measuringcord 4b thereto, isprovided, said measuringcord being passed through an eye in an arm 18 onsaid loose ring 17 and knot-ted at its end to prevent the withdrawal ofthe cord from said eye.

In operation the measuringcord being wound upon the drum thecenter-marking crayon is placed against the blackboard through thecentral opening in the protractor and is pressed against the latter, thethumb and foreflnger ofthe left hand of the operator or pupil retainingthe drum and preventing it from revolving until it may be desired. Whenthe drum is held from revolving and the marking-handle is used to drawupon the measuring-cord to inscribe the desired circles or parts ofcircles, the eccentric hinged to the arm of the revolving sleeve 3 isswung up against the measuring-cord and removes most of the strain uponsaid cord from the drum, thereby rendering the device comparatively easyof manipulation by a single pupil.

Although I have described my device in the best form known to me, itisobvious that many changes might be made in the construction withoutdeparting from the character of the invention, and I do not thereforelimit'myself to the precise construction herein described andillustrated.

Having thus fully described my invention, what I claim, and desire tosecure by Letters Patent, is-

1. In a compass-protractor, in combinati on,the handpiece having astationary sleeve; a spring within said stationary sleeve; a slottedcrayon-holding tube working in said stationary sleeve and retainedtherein by a crosspin traversing said slotted sleeve; a cordwindingdrum; a revolving sleeve provided with a cord-guiding arm having aneccentric clamp hinged to its upper face, said revolving sleeve beinginterposed between said cordwinding drum and said stationary sleeve;substantially as specified.

2. In a compass-protractor, the combination with the axially-boredcrayon-holder having one end provided with crayon-holding fingers andthe sliding finger-clamping sleeve provided with separated encirclingrings; the loose ring mounted between said encircling rings and providedwith an arm having an eye therein for attaching one end of ameasuring-cord thereto; substantially as specified.

3. In a compass-protractor, the combination with the protractor properand the handpiece having the winding-drum and the rotary sleeve providedwith the integral arm having the cord-guide and the eccentric cordclamp;of the crayon-holder provided with the holding-fingers; the nger-clampsleeve provided with the loose ring having the cordattaching arm; andthe measuring-cord connecting said attaching-arm with the windingdrum onsaid handpiece; substantially as specified.

In testimony whereof I have hereunto set my hand in presence of twosubscribing wit- IIBSSGS.

JOHN D. BARBIE. Witnesses:

GEO. D. WOLFREY, CHARLES A. TAIT.

